yes there is a way. i worked with a boxing program where we had a device that measured some units of force at impact (i belive it was custom made and not commonly sold on the regular market).
Power=Force x velocity
(velocity is displacement [or distance] / time)
so, to find true power you would need a device to measure force, the distance travelled and the time it had taken to travel that distance).
or ... you could work on technique and simply trust that you're getting more "powerful"